The objectives of the Cerebrovascular Research Center at The Johns Hopkins University School of Hygiene and Public Health are the elucidation of risk factors for cerebrovascular disease and an attempt to describe the natural history and epidemiology of cerebrovascular disease. Research has emphasized geographic variation of stroke within the United States, trends in mortality, relationship of stroke to the use of oral contraceptives, familial aggregation, and relationship of urinary salt excretion to stroke. Additional studies are concerned with the natural history of transient ischemic attacks and the relationship of cigarette smoking to stroke.